AMPHIPODA 529 



form. These have the inner margin of the finger smoothly concave. In Dana's figure 

 the finger has a sHght convexity near the base, and also has a produced apex, corres- 

 ponding with a long groove in the sixth joint, which in a manner recall the same 

 features in Orchestia platensis. 



Dana gives the fjagellum of the first antennae three-jointed. This variable feature 

 has sometimes five joints. The ultimate and penultimate joints of the peduncle of the 

 second antennae are much stouter than in any of the specimens referred to Orchestia 

 platensis, and yet the flagella are not more than fourteen-jointed. It seems unlikely 

 that the larger and more strongly armed male should have a shorter flagellum than a 

 less highly developed male of the same species. The specimens referred to Orchestia 

 pickeringii have the fourth and fifth joints of the fifth peraeopods, though not dilated, 

 thickened in a way not exhibited by the other set. This, however, might be a 

 character of advanced maturity. 



Length reaching 14 mm. 



One female specimen, 12 '5 mm. long, which I am inclined to refer to this species, 

 differs from those of the same sex referred to Orchestia platensis in rather superior bulk, 

 and also in having a distal boss on the fourth joint of the second gnathopods, agreeing 

 in that respect with Dana's figure of the limb in question in Parorchestia haivaiensis, $. 

 From that species it is completely distinguished by the short, few-jointed, upper 

 antennae. 



Gen. Parorchestla., Stebbing. 



1899. Parorchestia Stebbing, Trans. Linn. Soc. London, vol. vii, pt. 8, pp. 397, 



402. 

 This genus was instituted to receive three of Dana's species of Orchestia, namely, 

 temiis, haivaiensis, and sylvicola. 



Parorchestia haivaiensis Dana. 



Plate XXI. C. 



1853. Orchestia haivaiensis Dana, U.S. Expl. Exp., Crustacea, pt. 2, p. 880, 



pi. 59, f. 8 a— g. 

 1899. Parorchestia haivaiensis Stebbing, Trans. Linn. Soc. London, vol. vii, 



pt. 8, p. 402. 

 Dana's description and figures of this species, obtained at ' Oahu or Kauai, 

 Hawaiian Islands,' refer only to the female. Specimens of both sexes obtained by Mr 

 Perkins were labelled as coming from " Koholuamano, Kauai," and from " Waianae 

 Mts., Oahu." It has also been taken by Dr Arthur Willey at Lifu. 



